FORT COLLINS - All of the mature lodgepole pine trees in Colorado will be dead within five years, federal and state officials said on Monday.

The announcement revealed that an "epidemic" of mountain pine beetles is destroying the state's forests.

"This is a huge, unprecedented event," said Rick Cables, Rocky Mountain Regional Forester for the U.S. Forest Service.

Officials said beetles infested 500,000 acres of lodgepole pines in 2007 alone, for a total 1.5 million acres statewide. Before last year, the beetles had largely infested trees in the higher elevations of the Rockies, particularly Grand County.

However, aerial surveys showed major infestations north of Leadville, and into Gilpin and Clear Creek counties. And Boulder and Larimer Counties saw a 1,500 percent increase in infested trees last year, officials said.

The infestation "blew up" in Larimer County last year, especially in and around the Rawah Wilderness, experts said.

"We were kind of expecting it," said Ingrid Aguayo, an entomologist with the Colorado State Forest Service, based in Fort Collins. "But were still really surprised. In the Rawah, that's where, as we call it, it blew up."